Electric frequency controlled color phosphor screen



H. A. MlCHLlN July 10, 1962 ELECTRIC FREQUENCY CONTROLLED COLOR PHOSPHORSCREEN Filed Sept. 18. 1957 T/COLOR SIGNAL FIG. I

m R LC! M m m m SR CONVERTER SIGNA L TO \RA DIO FREQ.

CONVERTE R if r ELECTRON GUN 8\ DEFLECTING MEANS RADIATION SOURCEPIC-3.2

RADIO FREQ.-

SOURCE ELECTRIC OR RADIATiON I SOURCE I 3&4338? Patented July 10, 19%2United States Patent Orifice 3,943,987 ELECTRIC FREQUENCY CONTROLLEDEOLGR PHOSPHGR SCREEN Hyman A. Michlin, 1575 Udell St., New York, N.Y.

Filed Sept. 18, 1957, S61. No. 684,768 10 Claims. c1. 31s 2s inventionrelates to color phosphor screens, and particularly toelectroluminescent and electrophotoluminescent different color emittingphosphor screens in which the color is selectively controlled byelectric frequencies for use as information display screen.

One object of this invention is to provide method and means forcontrolled color emission of selected elemental areas by excitation andelectric frequency control to produce color images.

Another object of this invention is to provide method and means forcontrolled color emission to produce color images in sequence byselected electric frequency application. V 7

Another object of this invention is to provide method and means forcontrolled color emission by a raster of elemental areas .of electricfield modulated in intensity and frequency. 7

Another object of this invention is to provide method and means forcontrolled color image changes efiected in one phosphor screen bychanging electric frequencies.

Other features, objects and advantages of the invention .will beapparent from the following specification, taken in connection with theaccompanying drawings in which: FIGURE 1 schematically illustrates onemode of the invention; FIGURES '2 and 3 schematically illustrate 'another mode of the invention in both front'and side views; and FIGURE 4schematically illustrates anothermode of the invention. a

Referring to FIGURE 1, by way of example. Screen target comprisestransparent conductive layer 1 electrically connected to positivepotential from potential source 6,- phosphor layer 2 made up ofphosphors capable of luminescing in a selective variety of colorsindependently of the source of excitation and under the control ofelectric frequencies applied in accordance with phosphors described inPatent No. 2,780,731 and schematically represented in FIGURE 2 thereof,the transparent insulation layer 3, and the anisotropic conductive layer4. The said anisotropic conductive layer '4 is electrically connected topotential source 6 so as to maintain the potential charge on theanisotropic conductive layer 4 constant The anisotropic conductive layeris defined in this application as an arrangement of substances havingthe property of having an image in electron charges electri cally orelectronically produced on one surface thereon and transmitting andmaintaining the said image therethrough. The anisotropic conductivelayerfcan be an arrangement of substances such as globules of metal onan insulative surface as in the iconoscope mosaic; such as elementalislands of conductors separated by insulation, for example, thetwo-sided mosaic described in Television, by Zworykin, page 302; and,such as the two-sided target made up of thin sheet of glass as describedon pages 425-426 of the Proceedings Institute of Radio Eng. (1946). Thecharacteristics noted above are known as aeolotropic or anisotropicconductivity.

The picture tube isconventional having electron beam generating,modulating and scanning means. High pres sure mercury lamp 7 irradiatesthe phosphor layer 2 with ultra-violet rays to excite same tophotoluminescence. The source 7 can also be suitably positioned so as toscan the phosphor layer through the transparent conductive layer 1. Thecolor picture signal representative of the resultant color of each colorpicture element is transmitted from source 10 to radio frequencyconverter 8,

which can be conventional, for example, Where the color signal varies inintensity or level of potential, then each potential level could beelectronically converted by known means to radio frequencies dependingon the instant intensity or potential level of the color signal. Thisradio frequency would then be representative of the color to be producedwhich impressed on an elemental area of the transparent anisotropicconductive layer 4 would impress the instant radio frequencies on acorresponding elemental area of the phosphor layer 2 so as to reproducethe color; and the signal representative of the degree of light requiredfor the same picture element from source 9 modulates the electron beamsimultaneously with the radio frequencies modulating the electron beamto thereby produce a scanning electron beam at that instant of suchintensity and radio frequency impacting sequential elemental areas ofthe anisotropic layer 4, and so to the phosphor layer 2 so as toreproduce the color and the intensity of light emission in correspondingareas of the phosphor layer.

In operation the ultra-violet rays from source 7 excites the phosphorlayer 2 to photoluminescence, and positive potential is applied to theanisotropic conductive layer 4 and higher potential is applied to thetransparent conductive layer 1 from the source 6; and the instantimpacting electron beam 11, modulated by color and light intensitysignal from source 9, is scanned to sequentially impact elemental areasof the anisotropic conductive layer 4 so as to impress radio frequencyfields in such intensities on corresponding elemental areas of thephosphor layer 2 'so as to cause colors to be emitted representative ofeach color picture element and to reproduce the intensities of lightemissions of each color picture element; so that by synchronousmodulation of the electron beam by a linear signal representative of acolor picture with the systematic scanning of the electron beam thecolor picture is reproduced.

To describe one modification reference is made to the schematicillustration in FIGURE 1 where the direct electrical connection betweenthe source 6 and the transparent conductive layer ,1 is omitted, and thesignal to radio frequency converter 8, schematically illustrated by dashlines, is inserted in the conducting path between the potential source 6and the transparent conductive layer 1 so that where the color signalfrom source 10 is representative of the field-sequential-color-system,then the radio frequencies, in accordance with the color to'be emittedfrom the phosphor screen, is eifected by the intensity levels of eachfield-sequential-colorv signal from source 10, and the radio frequenciesproduced therefrom modulates the. positive potential transmitted to thetransparent conductivelayer 1 from source 6 to thereby control the coloremission from the phosphor layer 2, while theelectron beam 11 ismodulated by the light intensity signal'from source 9 to therebyreproduce the color picture.

Another example of the invention is schematically illustrated in FIGURE4 where excitation is by ultra-violet rays from source 7, and electricalconnection to the anisotropic oraeolotropic conductive layerd isomitted; and the scanning electron beam 11, modulated by light intensitysignal and color signal both representative of the color pictureelements of a color picture, impacts sequential elemental areas of theanisotropic conductive layer 4 to betransrnitted through elemental areasthereof to be impressed on corresponding elemental areas of the phosphorlayer 2 so as to quench or control the light emitted; and, by virtue ofthe known property of phosphors under excitation/becoming moreconductive, the electric charges on each elemental area of theanisotropic or aeolotropic conductive layer 4 isneutrali zed bytransmission through the phosphor layer 2.

Referring to FIGURES :2 and 3, for purpose of example. Theelectroluminescent phosphor screen 13 comprises, for example,electroluminescent phosphor ZnS:Cu,Mn which is caused to progressivelychange its color emission from yellow to blue on being subjected toincreased electric frequencies from 50 c.p.s. to 500 c.p.s., andelectroluminescent phosphor ZnS:Cu,Pb which is caused to progressivelychange its color emission on being subjected from low to 2000 c.p.s. ofelectric frequencies from green towards the blue part of the spectrum.The letter T is composed of such phosphor mixtures as to emit ingreenish yellow at 50 c.p.s. and bluish green at 500 c.p.s. Thebackground 12 is of such phosphor mixture as to emit green at 50 c.p.s.and bluish green at 500 c.p.s., and sufficiently close in color to thebluish green color emitted from the letter T as to cause the letter Tnot to be very clearly discernible. The electric frequency source 14 canbe conventional means for producing electric frequencies in changingcycles per second from 50 c.p.s. to 500 c.p.s. to thereby efiectchanging color emission and thereby cause information of the letter tobe rendered clearly visible at one time, and to a point of emissionwhere it is hardly discernible at another time. The layer 15 is a metalelectrode layer, the layer 1 is a transparent conductive layer, and thelayer 3 is an insulation layer.

To describe an example of an operation, reference is made to FIGURES 2and 3. The electric frequency source 13 generates electric fieldsvarying in frequencies from 50 c.p.s. to 500 c.p.s. so as to produce achanging display of information.

The above is only by way of example and is not intended to berestrictive as many modifications can be made; for example, thephosphors in FIGURE 2 can be used in the example schematicallyillustrated in FIGURE 1; and the phosphors used in FIGURE 1 can be usedin the example schematically illustrated in FIGURE 2.

While the present invention has been described with reference toparticular embodiments thereof, it will be understood that numerousmodifications may be made by those skilled in the art without actuallydeparting from the invention. Therefore, I aim in the appended claims tocover all such equivalent variations as come within the true spirit andscope of the foregoing disclosure.

I claim:

1. The method for producing a color image in a phos phor target,elemental areas of which emitting in a desired color depending on itsexcitation to luminescence and on a selected frequency of electricfields impressed thereon, which comprises the step of uniformly excitingthe phosphor target, an the step of systematically and se-' lectivelyapplying a frequency varying of potential differences to each elementalarea of the phosphor target to vary the. color of emission from eachelemental area of the phosphor target.

2. The method for producing colors in a pattern from an intermixture ofdifferent color emitting phosphors, each different color emittingphosphor controllable in intensity a selected different frequency ofelectric fields to each sequential elemental area of the phosphor layerin turn so as to effect an intensity and selection of color from eachsequential elemental area thereby producing the In minescent colorimage.

4. An apparatus for producing an electroluminescent color imagecomprising an envelope, means to generate, modulate and scan an electronbeam therein; and a target comprising an anisotropic conductive layer, aphosphor layer and a conductor layer in the order named with the freeside of the anisotropic conductive layer arranged to be impacted by saidscanning electron beam; the phosphor layer having the characteristic ofvarying its color emission in accordance with the frequency of electricfields applied thereto; means for selectively varying the electronenergy of the scanning electron beam impacting each elemental area ofthe anisotropic conductive layer for a successive interval of timethereby impressing an image in electric frequencies in potentials on theanisotropic con ductive layer; and means for applying a potential to theconductor layer thereby on the application of suflicient potentialdifferences between the potentials applied to the anisotropic conductivelayer and the potential applied to the conductive layer a color image isproduced.

5. The apparatus of claim 4 for producing an electrophotoluminescentcolor image in which the phosphor layer has the characteristics of beingexcited to luminescence and changing its color emission in accordancewith a selected frequency of electric fields applied thereto; andcomprising in addition an excitation source for exciting the phosphorlayer to luminescence thereby producing an electrophotoluminescent colorimage.

6. An apparatus for producing changing electroluminescent colors in atleast one pattern comprising a phosphor layer, one conductive layer onone side and one conductive layer on the other side of the phosphorlayer; the phosphors in said phosphor layer of such characteristics thata selected frequency of electric fields applied thereto will result in aselected color emission, and on varying the frequency of electric fieldsapplied thereto will effect a varying color emission; the phosphorsarranged in such intermixture as to emit in a selected color pattern;and means for applying changing frequencies of potential differences tothe conductive layers thereby producing changing electroluminescencecolors in at least one pattern.

7. The apparatus of claim 6 in which the phosphors can be excited toluminescence and have the same color emission control characteristics byapplication of different frequencies of electric fields thereto, andcomprising in addition a radiant energy source for exciting the phosphorlayer.

8. An apparatus for producing an electrophotoluminescent color imagecomprising a phosphor layer sandwiched of color emission in accordanceWith excitation thereof I to lurniniscence and with a selected frequencyof electric fields in the radio wave spectrum applied thereto comprisingselectively arranging the different color emitting phosphors in a layerto emit in at least one desired color on application of excitationenergy thereto; uniformly exciting the phosphor layer; and applying animage in different frequencies of electric potential difi'erences in theradio wave spectrum to the phosphor layer thereby producing colors in apattern.

3. The method for producing a luminescent color image from a phosphorlayer the phosphors of which on excitation thereof are capable ofchanging color emission under control of selected frequencies ofelectric fields applied thereto, and the intensity of color emissiondepending on the potential differences applied thereto comprisinguniformly exciting the phosphor layer; and systematically andsimultaneously applying such potential differences and between ananisotropic conductive layer and a conductive layer, said phosphor layerafter excitation to luminescence emitting in a selected color inaccordance with the frequency of electric fields applied thereto; anexcitation radiant energy emission source adapted to irradiate thephosphor layer to excite same to luminescence; means for applying apotential to the conductive layer; and means for applying, on the freesurface of the anisotropic conductive layer, a pattern in differentelectric field frequen- 1 cies in potentials different from thepotential applied to the conductive layer whereby producing an electro-5 target comprising a phosphor layer sandwiched between an 2,440,301anisotropic conductive layer and a conductive layer, said 2,446,248phosphor layer emitting in a selected color in accordance 2,452,522 withthe frequency of electric fields applied thereto; said 2,684,885anisotropic conductive layer adapted to be impacted by 5 2,773,216 saidelectron image; means for applying a potential to the 2,780,731conductive layer; and means for causing the electron 2,795,730 image tobe an image in difierent frequencies of varying 2,881,353

electron energies whereby on impacting said electron energies on theanisotropi cconductive layer an image in elec- 10 tn'c potentialsdifierent from the potential applied to the conductive layer is'efiected whereby producing an electroluminescent color image.

References Cited in the file of this patent UNITED STATES PATENTS2,239,887 Ferrant Apr. 29, 1941 a 6 Sharpe Apr. 27, 1948 Shrader Aug. 3,1948 Leverenz Oct. 26, 1948 Nakken July 27, 1954 Edmonds Dec. 4, 1956Miller Feb. 5, 1957 From et a1 June 11, 1957 Michlin Apr. 7, 1959 OTHERREFERENCES Destriau: Electroluminescence and Related Topics, Proceedingsof the I.R.E., December 1955, vol. 43, No. 12, pages 1911 to 1940.

McKenzie: Electrons at Work, Electronics, November 15 1956, vol. 29, No.11, pages 190 and 192.

